Process of producing nitrides of aluminum or magnesium from their minerals



May 5, 1931.-

Dusv L'mwaew I z HEAT Excwmssn PR0 nu c ER "Gas C. G. MINER PROCESS OF PRODUCING NITRIDES 0E ALUMINUM OR MAGNESIUM FROM THEIR MINERALS Filed July 6, 1926 Eusc-rnooz .5 Bmuew: 0F Bnuur:

AND Cone Cminema Fuwn Conausnon uenrma C/mmmunoun g I 0091- Cmmazk Hz" Excmuosn Hwonv ER GAS rBocEss or rnonuome NIrmnEs' 1 efiiciency for-the production ofjaluminum or I magnesium nitride: from the1r m1nerals.

Patented May 5, 1931 luNITEn- PATENT OFFICE cimunn e}. M nna, or BERKELEY, CALIFORNIA or ALUMINUM onmaennsrum FROM MINERALS 1 THEIR Application and July 6,1920. serial No. 120,683. a I

This invention relates to the production .of aluminumfand' magnesium nitrides from their minerals. V

The principal object ofthis invention is to provide a method or process of increased Anotherobject of this invention is to pro- "site at about; 1800 vide an apparatus for carrying out the process embodying this invention. v

It is known that carbonaceous materials .1 will reduce both the oxide of aluminum and Inagnesium.. For the pure oxides of aluminum or magnesium, the active reduction temperature 1 is approximately" 2000 C.

For the impure oxidesjthe reduction temperature is somewhat .lower. For example,

coke will reduce'oxide and calcined magne-,

oxides, the reaction is r V 1."A l 0=;-i-3C='A1 3CO For the'm'agnesium oxides, the reaction 'amorsw wb ing to the above reactions 1" and 2 by lowering the temperature of the resultant gases,

then in each case, as is well known, the

above reactions lreverse to produce the origi;

n nal .jproductsz lReduction of theabove oxideshas been carried on and the resultant gases diluted with hydrogen, in which case.

as high as 190% aluminum and magnesium metal has been obtained, 1

' though other temperatures without this.

In accordance with my present invention,

range'inight be employed; In the case of the preparation of aluminum nitride, I pro-' poseto use bauxite alunite residue and other alumina bearing minerals, while in the case. of the preparatlon of magnesium nitrlde, I,-

propose to use calcined magnesite dolomite,

or other magnesium ores.

V :1 After the minerals, have been reduced in :accordance with reactions 1 or 2, the result-- ant gases, without-being allowedto coolto.

C. For aluminum the conduits 4.'

the reversal temperature, are brought into 7 1 and the metal in the vapor phase is carried out of the reduction zone 1 through outlets 2 into a reaction chamber 3. The resultant carbon gases formed during the carrying out In this apparatus, reactions 1 or 2 are carried out 1n the reduction chamber or zone of reactions 1 and 2 pass with the metal in the vapor phase through the outlets 2 into thereaction chamber 3. A nitrogen bearing gas is introduced into the gases as the same; pass from the reduction zone 1 into the reaction chamber 3, care being takennot to introduce the nitrogen bearing gas into the reduction zone 1, but the nitrogen bearing y r v 7 V n gas is not introduced into the gaseous prod-"- If attempt ismade to condense out the aluminum or magnesium produced accorducts, produced in accordancewith reactions 1 or 2 in the reaction zone 1, until the said gases pass into the reaction chamberB.

The reaction chamber 3 isat a lower temperature than the'reduction zone 1. If the gaseous products produced into the reduc-- tion zone 1 are mixed with the" nitrogen bearing gas, as illustrated in the drawings, no specific temperature is required in the reaction chamber. The reaction between the nitrogen and the metal in the metallic'phase is exothermic and the" temperature in the reaction chamber is maintained by the heat produced by the reaction between the metal and the nitrogen. These reactions may be illustrated as: V

, 3. Al +3C0+N +.52CQ=Al N +3.52CO I 4.eM +cco+2N +1.04co=2M m+mo4oo 7 Reactions 3 and 4 may be the reactions which take place when producer gas is in troduced into the reaction chamber, through 7 It is preferable that the reaction chamber 3 be formed surrounding thereduction zone 1 so that the heat of the reaction between the metal in the vapor phase produced in the reduction zone 1 with the nitrogen introduced into the reaction chamber aids in maintaining the requisite temperature in the reduction zone 1. This utilization of heat of reaction it is believed will enable the nitrides of aluminum and magnesium to be produced commercially.

The apparatus dlagrammatically illustrated in the drawings is applicable for the production of either aluminum (nitride or magnesium nitride and will be described in connection with the production or its application to the production of al'u'lninum nitride.

Briquets formed of ground bauxite and coke, or other aluminum bearing minerals and coke, is introduced through a hopper 5 into a surface pre-combustion and pre-hea ting zone 6 where the briquets are pre-heated by the waste gases which pass from the reduction zone 1. During this pre-heating, surface combustion of the briquets takes place, due to the raised temperature thereof. In order to support and maintain this combustion within the surface combustion and pre-heating zone 6, the carbon gases produced within the reduction chamber 1, after the same have been conducted to. the reaction chamber 3, are conveyed through a conduit 7 through a heat-exchanger 8 and dust collecting chamber 9 into the zone 6 and air is introduced into the zone 6 through the inlet 10. The air and carbon gases are burned within the zone 6. The pro-heated mineral passes from the zone 6.into the .reduction zone 1 on the withdrawing from the lower end of the zone 6 of a graphite or like material plug 11. Electrodes 12, connected with any suitable or desirable source of electric current, extend into the reduction zone 1 for the purpose of maintaining the required temperature within the reduction zone 1. The aluminum metal formed during the reduction of the alumina bearing mineral within the reduction zone 1 vapor- 1zes and passes through the outlet 2 into the reaction chamber 3 with the carbonaceous gases produced during the reaction 1. lBroducer gas or a similar nitrogen containing gas is introduced into the gaseous products through the conduit 4 and the reaction takes place in the reaction chamber 3 and aluminum nitride is drawn oif through the outlets 13. The carbon gases, as before described, are conducted in the reaction chamber 3 through the conduit 7. The dust that tends to pass with the gases from the reaction chamber 3 is collected in the dust chamber 9 and the heat of the gases passing from the reaction chamber 3 maybe utilized in a heat exchanger 8 for the pre-heating of the air introduced through the inlet 10 or for the pre-heating of the briquets or alumina bearing mineral and coke which is intronitrides duced into the apparatus through the chamber 5 or may be utilized in any other manner desired.

The gases produced in accordance with reaction 1 or 2 in the reduction zone 1 are allowed to escape around the electrodes 12 so I claim: 1. A process of producing metallic nitrides which comprises reducing the metallic oxide to the metal in a reducing zone at the volatilization temperature of the metal, conducting the vaporized metal and resultant gases from the reducing zone to a reaction zone apart from the reducing zone,

and mixing a nitrogen-bearing gas with the vaporized metal in the reaction zone to produce the metallic nitride.

2, A process of producing metallic nitrides which comprises reducing the metallic oxide to produce .a vapor of the metal, conducting the vaporized metal from the reducing zone and then mixing a nitrogen-bearing gas with the vaporized metal and allowing the mixture to cool.

3. A process of producing metallic nitrides which comprises reducing themetallic oxide to the metal in a reducing zone at the volatilization temperature of the metal, conducting the vaporized metal and resultant gases from the reducing zone into a reaction zone apart from the reducing zone, and: introducing a nitrogen-bearing gas of a reducing character into the reaction zone to react with the vaporized metal to produce the metallic nitride.

4. A process of producing metallic which comprises reducing the metallic oxide to the metal in a reducing zone, conducting the vaporized metal and resultant gases from the reducing zone to a reaction zone apart from the reducing zone, mixing the nitrogen-bearing gas with the vaporized metal so that the nitrogen and the vaporized metal react at a temperature lower than that existing in the reducing zone but. at a temperature higher than the volatilization temperature of the aluminum,

conducting the vaporized aluminum and resultant gases from the reducing zone to a reaction zo'ne apart from a reducing zone and introducing a nitrogen-bearing gas of reducing character into the reactlon zone to react with the vaporized aluminum to produce aluminum nitride.

Signed at San Franciscc this 16 day of June, 1926.

CLAUDE G. MINER. 

